Photo-electrochemical cell

Abstract

The regenerative photo-electrochemical cell comprises a polycrystalline metal oxide semiconductor layer having a substantially monomolecular chromophore layer in a surface zone. The surface of the metal oxide semiconductor layer has a roughness factor of more than 20, preferably more than 200. Photo-electrochemical cells having such metal oxide semiconductors have good monochromatic efficiency using redox systems with iodides or bromides.

What is claimed is: 
     
       1. A regenerative photo-electrochemical cell comprising a polycrystalline metal oxide semi-conductor having a surface with a roughness factor of more than 20; and   a monomolecular chromophore layer on said surface of said semi-conductor.   
     
     
       2. A regenerative photo-electrochemical cell as set forth in claim 1 wherein said semiconductor is made of a material selected from the group consisting of at least one of an oxide of a transition metal, an element of the fourth, fifth or sixth secondary groups, an oxide of zinc, iron, nickel or silver, a perovskite, and a perovskite of said metals. 
     
     
       3. A cell as set forth in claim 1 wherein said semi-conductor is made of a material selected from the group consisting of titanium, zirconium, hafnium, strontium, zinc, indium, yttrium, lanthanum, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. 
     
     
       4. A cell as set forth in claim 1 wherein said semi-conductor is made of a material selected from the group consisting of SrTiO 3  and CaTiO 3 . 
     
     
       5. A cell as set forth in claim 1 wherein said chromophore layer is formed of transition metal complexes. 
     
     
       6. A cell as set forth in claim 5 wherein said chromophore layer is made of a transition metal complex selected from the group consisting of ruthenium tris (RuL 3 ), ruthenium bis (RuL 2 ), osmium tris (OsL 3 ), osmium bis (OsL 2 ), and ruthenium cis diaqua bypyridyl complex of the type RuL 2  (H 2  O) 2 . 
     
     
       7. A cell as set forth in claim 6 wherein said chromophore layer is made of ruthenium cis diaqua bis (2,2'-bipyridyl-4,4'-dicarboxylate). 
     
     
       8. A photo-electrochemical cell as set forth in claim 1 wherein said chromophore layer is made of phthalocyanine or porphyrin of metal or non-metal. 
     
     
       9. A regenerative photo-electrochemical cell as set forth in claim 1 further comprising carboxylic acid ligands bonding said chromophore layer to said semi-conductor layer. 
     
     
       10. A regenerative photo-electrochemical cell as set forth in claim 1 further comprising an electrolyte layer on and over said chromophore layer, said electrolyte layer having at least one of an iodide, bromide, and hydroquinone therein. 
     
     
       11. A regenerative photo-electrochemical cell for converting sunlight to electrical energy comprising a polycrystalline metal oxide semi-conductor layer having a photo-electrochemically active surface with a roughness factor of more than 20; and   a monomolecular chromophore layer on said surface.   
     
     
       12. A cell as set forth in claim 11 wherein said active surface has a roughness factor of more than 150. 
     
     
       13. A cell as set forth in claim 11 further comprising an electrolyte layer on said chromophore layer and an electrode on said electrolyte layer. 
     
     
       14. A cell as set forth in claim 13 further comprising a metal support having said semi-conductor layer thereon. 
     
     
       15. A solar cell comprising a polycrystalline metal oxide semi-conductor layer having a photo-electrochemically active surface with a roughness factor of more than 20;   a monomolecular chromophore layer on said surface;   an electrolyte layer on said chromophore layer;   an electrode on said electrolyte layer; and   a support having said semi-conductor layer thereon.